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Venus and Regulus

The evening star has a date with the lion the next couple of nights. They’re due west as the color of twilight begins to fade away, and set a couple of hours later.

The “evening star” is Venus, our closest planetary neighbor. It’ll snuggle close to the star Regulus, the heart of the constellation Leo, the lion.

Venus and Regulus line up together because they both lie near the ecliptic, which is the Sun’s path across the sky. Regulus, in fact, is only about half a degree from the ecliptic -- a position that it maintains all the time. From that fixed location, it encounters the Moon about once a month, and the planets at varying intervals.

Venus stays close to the ecliptic, too. Its orbital path is tilted a bit with respect to the ecliptic, though, so Venus moves from one side of the ecliptic to the other. But it’s never more than a few degrees away from it.

On rare occasions, Venus can actually cross between Earth and Regulus, briefly blocking the star from view. The last time that happened was 59 years ago today -- July 7th of 1959. And it won’t happen again until October 1st of 2044.

These eclipses are so rare for a couple of reasons. One is that Venus and Regulus generally pass each other no more than once or twice a year. Another is that Venus moves back and forth across the ecliptic. And finally, Venus covers a small area of the sky, so the alignment has to be perfect for Venus to cover up the lion’s mighty heart.

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